(February 22, 2012) -- The game of tennis has never been kind to the aging. Players sacrifice their bodies and often their personal lives for a sport that repays them with aching joints, fond memories and, if they’re lucky, some money in the bank.

But the over-30 crowd has been taking advantage of an era seemingly better suited to those with fully developed games. Of course, a career’s-worth of experience doesn’t hurt either. At the U.S. National Indoor Tennis Championships taking place this week in Memphis, five players on the men’s side are over the age of 30, with one quarterfinalist, Michael Russell, nearing the 35-year mark.

So what is it, then, that makes Andy Roddickretireon the eve of his 31st birthday with a ranking still inside the top 25, but keeps 33-year-old James Blakeplugging awayon the Challenger Circuit? What is it that makes Pete Sampras retire less than a year after winning his 14th Grand Slam, but keeps Lleyton Hewittfighting back from his fifth surgery in four years?

Tommy Haas, a 17-year tour veteran and former world No. 2 (in 2002), is fueled by the thrill of victory.

“The satisfaction of winning matches, going out there and finding a way to win, it gives you satisfaction. It’s like nothing else, really,” he told Tennis Now. “It’s crazy…it’s like an unbelievable suspenseful thriller movie, and that’s fun in some ways as long as you can deal with it.”

After reaching the recent San Jose final, Haas’ ranking has climbed inside the top 20 for the first time since 2010, coming an astounding 14 years after he first entered the top 20 in 1999. But life has changed significantly for Haas since then. In addition to enduring multiple surgeries, he became a parent with fiancée Sara Foster.

In a Memphis press conference following his opening round victory, Haas was interrupted by a FaceTime call from his daughter. He answered his phone immediately, his family understandably beating out a room full of journalists. But, of course, it’s not always that easy to make relationships a top priority with players often continents away from their loved ones.

Michael Russell turned pro in 1998 and married his wife Lilly in 2007. Though they’ve made the most of their arrangement, often renting a condo in tournament cities so they can feel as close to “normal” as possible, Russell acknowledged the difficulty in maintaining a healthy marriage on the pro tour.

“It’s hard to have a relationship when you see the person one week out of every month,” he said. “It’s not realistic, because then when you’re not playing, it’s like, ‘Oh, wait…we’re together 24/7.’ What happens then?”

At 5’8”, 155 lbs., Russell isn’t the most physically imposing player on tour, but he is, without a doubt, one of the hardest workers. Without size on his side, the self-described fitness “freak” relies on years of experience and a heavy dose of self-discipline. He says he takes his tennis career one month at a time, though the Detroit native admits he’d like to surpass his career-high ranking of 60 as well as reach the $2 million dollar mark in career prize money.

Russell’s bulldog mentality is similar in some ways to Lleyton Hewitt’s, who made his name – and most recently a clothing line – on his signature “Come On!” battle cry. But unlike Russell, Hewitt has had a taste what life is like at the top, making his decision to continue playing on tour with a current rank of 107 a bit more puzzling. The former No. 1 and father of three says he doesn’t worry about his ranking, choosing instead to focus on Australian Davis Cup and his performance in the Grand Slams.

“My good mate Pat Rafter is the captain for Australia. It would mean a lot to me to be a part of the team to get us back in the World Group…Pat wants me to play another four or five years, but that won’t be happening,” he said with a laugh.

Much like Haas, Hewitt has been sidelined several times with various surgeries, most recently facing a potentially career-ending foot operation. Despite the “6 or 8” screws now implanted in his toe, Hewitt fought his way back into playing shape, looking at his recovery like a battle to be won; much like he looks at a tennis match. As long as his body is holding up, Hewitt says he doesn’t talk much to his wife, Australian singer and actress Bec Hewitt, about “the end.” But there’s one thing he’ll miss when retirement finally beckons.

“For me, it doesn’t get any better than walking out to play center court at the Australian Open or Wimbledon. I love playing on those big arenas.”

Unique as their stories may be, all three of these men have pondered what’s next in their lives; all three mentioning possible second careers in business. And when fans wonder why they would choose this lifestyle after so many years of the pro tennis grind, perhaps the best answer is, “Why not?” Why not ride the wave of professional sport as long as it will carry them?

Whatever they choose to do next, Russell, Haas, and Hewitt have one more thing in common: They all plan on using what Russell refers to as a “Ph.D” in tennis to give back to the sport that’s been the source of both their pain and their passion.